This invention relates to a method of a gasoline additive producing and more particularly a process for manufacturing gasoline additives of ester-free polyoxyalkylene-amide which is advantageous for decreasing intake valve deposits, decreasing octane requirements, controlling internal combustion chamber deposits and improving fuel efficiency.
Many additives are known to be added in gasoline in order to prevent or reduce deposit formation. Recent related prior art is cited below:
Polyoxyalkylene amide:
U.S. Pat. No. 5,352,251 (Oct. 4, 1994) to Shell Oil Company, xe2x80x9cRing polyoxyalkylene amide as gasoline additivesxe2x80x9d.
U.S. Pat. No. 5,693,107 (Dec. 2, 1997) to Shell Oil Company, xe2x80x9cHydantoin polyoxyalkylene amide as gasoline additivesxe2x80x9d.
U.S. Pat. No. 5,492,546 (Feb. 20, 1996) to Shell Oil Company, xe2x80x9cFuel compositionxe2x80x9d.
U.S. Pat. No. 5,507,843 (1996) to Shell Oil Company, xe2x80x9cFuel compositionxe2x80x9d.
U.S. Pat. No. 5,489,315 (1996) to of Shell Oil Company, xe2x80x9cHydantoin polyether polyol as gasoline additivesxe2x80x9d.
U.S. Pat. No. 5,458,661 (1995) to Shell Oil Company, xe2x80x9cFuel compositionxe2x80x9d.
U.S. Pat. No. 5,458,660 (1995) to Shell Oil Company, xe2x80x9cFuel compositionxe2x80x9d.
Polyoxyalkylene amines:
U.S. Pat. No. 5,057,122 (Oct. 15, 1991) to Mobil Oil Company, xe2x80x9cA dilsocyanate derivatives composition as fuel additives and lubricantsxe2x80x9d.
Other documents include U.S. Pat. No. 4,604,103 (1986) to Chevron, U.S. Pat. No. 5,112,364 (1992) to BASF, U.S. Pat. Nos. 5,286,266 and 5,286,267 (1994) to Texaco, U.S. Pat. Nos. 5,286,478 (1993) and 5,203,879 (1993) and 4,810,261 (1989) and 4,747,851 (1988) to Texaco.
Polyoxyalkylene amine carbamates:
U.S. Pat. No. 5,321,460 (1994) to Chevron, xe2x80x9cLinear propylene oxide of polyoxyalkylene amine carbamates as a fuel compositionxe2x80x9d.
And also U.S. Pat. No. 5,322,539 (1994), 5,321,460 (1994), 5,192,335 (1993) to Chevron, U.S. Pat. No. 423,321 (1980) to Chevron, U.S. Pat. No. 5,103,041 (1992) to British Petroleum U.S. Pat. No. 4,568,358 (1986) to Chevron.
Others
U.S. Pat. No. 5,296,003 (Mar. 22, 1994) to Chevron, U.S. Pat. No. 5,298.039 (Mar. 29, 1994) to BASF, disclosing a gasoline fuel composition comprised a nitro-detergent and polyester as a carried oil compound, wherein polyester compound starter is dialkyl phenol.
U.S. Pat. No. 5,246,006 (1993) to Exxon and 5,089,029 (1992) to Kao Corporation, regarding acrylonitrile reaction to form a Guerbet alkyletheramino-alchohol by addition process and reducing process.
However, the above prior arts never mention the formation of a byproduct, polyoxyalkylene amide-ester as follows: 
Which may reduce the performance of the other gasoline additives in lessening intake valve deposits or increasing the octane requirement.
The object of the present invention is to provide a process for manufacturing gasoline additives of ester-free polyoxyalkylene amides which are advantageous for decreasing intake valve deposits, octane requirements, controlling combustion chamber deposits and improving fuel efficiency.
The present invention is directed to manufacturing gasoline additives of ester-free polyoxyalkylene amide from a three-step process, as in FIG. 1:
A. Amidation of low-molecular-weight polyoxyalkylene amine with ethyl acetate to form the corresponding amides.
B. Alkoxylation of the amide with 1,2-epoxybutane to form polyoxyalkylene amide and unavoidable byproducts as below: 
C. Selective hydrolysis of the above mixtures to remove the amide-ester byproducts and recover the desired amide alkoxylates.
The essential analytical method is to use FT-infrared to identify the presence of the byproducts, hence the ester-free amides should be free of the following indicative 1735 cmxe2x88x921 absorption: 
Those ester-amide byproducts are proven to be harmful to the engine. Therefore, in step(c), the removal of the esters is important to manufacture the effective gasoline additives. The hydrolysis must be selective to remove only the ester byproducts but remaining the following desired amide alkyoxylate with the indicative infra-red absorption at 1650 cmxe2x88x921. 
The selective hydrolysis process is one of essential part of this invention. For example, the amidation and alkoxylation to made diethylenetriamine-triamide-butoxylate (DETA triamide-BO) and its contaminated esters should be subjected to the selective hydrolysis step to remove the ester functional group. The process required the treatment of the product mixtures with 8 to 12 wt % HCl, preferably 10% at 90 to 100xc2x0 C. under the refluxing condition. The process is carefully monitored by analyzing the disappearance of ester Cxe2x95x90O Absorption peak (1735 cmxe2x88x921) by IR. The ester functionalities are removed and a polyalkylene amide or amine-amide is generated. The desired composition is further analyzed by a gel permeation chromatography showing a narrow molecular weight distribution.
The tests of intake valve coking simulator (IVCS), and thermal decomposition test and octane requirement reduction (ORR) showed excellent results for the ester-free products.